[foxnne]

Opening bytes that are not a well-formed .pixi crashed pixi with a segfault at 0x0, in File.loadFizzyZip. This was seen with 0.1.47 in a ReleaseFast fizzy, when the restart hand-over (KeptDocuments.openKept → loadDocumentFromBytes) gave back an art.pixi that fizzy's text editor had held.

Cause. When fizzydata.json was missing or no version of the format parsed, ext stayed undefined, and the loader went on to read its grid and its layers slice. In ReleaseFast that slice's pointer is null.

Fix. Reading the archive moves to src/fizzy_zip.zig, which is std-only and tested by zig build test. Every malformed input is error.FileLoadError:

• an archive that won't open (empty, garbage, truncated, a bad central directory), or that has no fizzydata.json/pixidata.json
• data that is no version of the format
• a zero or oversized grid (more than 16384² px), a v1/v2 grid that isn't whole tiles, no layers, an animation frame past the grid, or a v1–v3 fps ≤ 0 (@intFromFloat(inf) before)

In loadFizzyZip:

• A .layer entry must be exactly the canvas's pixels. A short one used to be read past its end.
• A .png layer must be the canvas's size.
• selected_layer_index counts only the layers that loaded. A skipped layer could leave it out of range.
• Zip entry buffers are freed (they leaked before).
• Old-version parses go in one arena that is freed (they leaked before).
• A document left with no layers is an error.
• A failure after the document is built calls deinit on it.

Tests (src/fizzy_zip.zig): empty, 4 KiB of random bytes, text, a bare end record, and a lone local header. Also assets/src/misc.pixi cut at about 512 points, a built archive cut at every byte, a corrupt central directory, a zip without a data entry, and malformed data of each kind above. The real file, and a v1 file with pixidata.json, still load.

Verified (rebased onto main: Zig 0.17, SDK 0.2.32): zig build test in Debug and ReleaseFast (14/14), zig build, zig fmt --check. The wasm target was not built locally. Not yet reproduced in a live fizzy restart.

🤖 Generated with Claude Code

[foxnne]

Closed by the maintainer's decision on 2026-10-21; the malformed .pixi guard is dropped for now. The branch stays.